Grate structure



Dec. 30, 1924,

521,296- H. B. HOLT v GRATE STRUCTURE Filed 192:5

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2 Sfieets-Sheet 1 W/T/VESSE'S gymwgwg Dec. 30, 1 24' 1,521,296

H; HOLT GRATE STRUCTURE Filed NOV. 9, 1923 2 Sheets-Sheet 2 FIBJI.

a oUQ B Patented Dec. 3Q, 1924.,

tamer HARRIS B. HOLT, OF DORMGNT, IPFBJNI SYLVE ASSiGNOB, TO ROSEDALE FOUNDRY &

MACHINE COMPANY, OF IPITT$BURG3E, PENNUYLVANIA. A COR-EORATION OF BENN- SYLVANIA.

GRATE STRUCTURE.

Application filed November 9, 1923.

To all whom it may concern:

Be it known that I, Hannrs B. How, re siding at Dormont, in the county of Allegheny and State of Pennsylvania, a citizen of the United States, have invented or discovered certain new and useful Improvements in Grate Structures, of which improvements the following is a specification.

My invention relates to improvements in grate structure, and specifically to the structure of endless-chain travelling grates, by which fuel is automatically carried into the chamber of a furnace, to be consumed there. Grates of this type are widely used, particularly in boiler furnaces.

Of recent years there has been a marked development in the nature of increase in the size of boiler units, and the demand has been made upon engineers to design furnaces oflarger and still larger dimensions. Until very recently a furnace ten to twelve feet wide has been considered a large furnace, but now there is demand for furnaces twenty feet wide and upward even to thirty-six feet wide. It appears that, other things being equal, appreciable economies may be realized by building one large furnace, rather than several small ones.

hen furnaces of such width as has been suggested are contemplated, it is desirable, with problems of structure and operation in mind, that the grates be made in sections, or, rather that, instead of a single grate, spanning the whole width, a plurality of grates be provided, arranged side by side, across the width of the furnace. 'l Vlien a plurality of grates are so brought together, it is necessary to provide support and guidance for the individualgrate components, and at each end of each component. At the side walls of the furnace chamber there is of course support and guidance for the grate sections, as is usual, but for the edges of the sections which are remote from the side walls, support and guidance must be provided. This support and guidance in termediate the furnace walls must take the form ofa low wall, and the exposed surface of this low wall, between the grate sections must itself be regarded as and treated as a stationary grate member. The problem then is to render this stationary grate member, disturbing to a minimum degree, but cooperative in maximum degree, in the functioning of the grate as a whole, I

Serial No. 673,708.

present a solution of the problem of this stationary grate member, in a structure which I believe to be efficient and durable. beyond what has gone before.

My invention is illustrated in the accompanying drawing in which Fig. I is a view in vertical cross section of a furnace pro- Vided with an endless travelling grate made in two parts or sections, with a support and guideways for the inner and adjacent ends of the grate sections, built according to and in embodiment of my invention. Fig. 11 is a section viewed from the same point as Fig. l, but drawn to larger scale, and illustratingthe invention in detail. Fig. III is a view in plan from beneath; Fig. IV is a view in side elevation; and Fig. V is a view in end elevation of-a certain channel memher hereinafter to be described. Figs. VI and VII are views in side and end elevation of a certain grate bar hereinafter to be described.

Referring first to Fig. I a furnace will be found illustrated there in outline, and in the lower part and forming the floor of the furnace chamber, two grate sections 1 and 2 will be recognized. These extend from the sides toward the mid-line of the furnace and there they are borne upon a stationary supporting wall 3. The grate sections will be understood to be of the endless travelling type mentioned, and it will be perceived that the grate members to which the numeralsl and 2 are immediately applied rest upon in such manner that they may travel upon ledges 4 and 5 formed upon supporting wall 3.

in Fig. I the minute structure of the grate is not developed, but in II this structure appears. The links, to which the numerals 1 and 2 are here particularly applied are articulated upon rods in usual manner to form an endless chain structure, and the links carry the grate-bars 6. The fuel-sustaining surface of the grate is constituted by the grate-bars 6 and the whole structure of chain and grate-bars together is pervious to air through interstices necessarily found in such a structure but carefully maintained of effective size, to allow access of air to the bed of fuel when borne by the grate, and in adequate quantity and in proper distribution to achieve combustion. The flow of air from beneath through the grate may be accomplished by forced or by natural draft,

but always a condition is brought about of relatively high pressure beneath the grate and relative rarelication above the grate. a condition under which there is flow of combustion-sustaining air through the grate and through the bed of fuel resting thereon. The wall 3 is provided with ledges or shoulders, in the form of angle irons l, 5 secured to it. Above these ledges the wall extends upward in a head which afiords a guiding partition between the grate sec-- tions on either side, and the upper surface of this waihhead extends in appron'iine ely common plane with the grate surface, and indeed forms functionally part of the grate surface of the whole assembly. Manifestly it would be undesirable to have the crown of this wall rising to a less heightthan the general surface of the grate. sections, for then groove would be formed between the sections, and, the bottom of the groove being stationary, there would be clogging by ashes. Preferably as shown the crown of the wall is arched somewhat, as best shown in Fig. H and rises in the middle somewhat above the general level of the grate sections. And, still bearing in mind the fact that this wall is stationary, this particular shaping of the crown is advantageous. in

that it tends to free this stationary surface of accumulation of ashes. J The accumulating ashes work laterally by gravity from the crown of the stationary wall to the moving grate sections.

The crown of the wall, in that it neces sarily forms part of the fuel-supporting surface, is treated as part of the grate. that end its upper face is made up of gratebars with air spaces, and provision is made for the flow of combustion-nourishing streams of air-through this portion of the grate, as well as through the moving por tion.

The details of structure appear in Figs. IIVH. The wall 3, which rises from suitable foundation, is surmounted by succession of castings 7, which, arranged end to end, constitute a deep channel throughout the length of the wall, and upon these castings rest the grate-bars 8. These grate-bars closethe channel above and convert 1t into a chamber extending throughout the length of the wall. The castings 7 are provided with openings 9 through their basal and medial webs, and in application these openings provide for the passage through of bolts 10 previously set in wall 3, and to these bolts the castings 7 may be removably secured by means of cotter-pins 11. Through the side webs of castings 7 openings 12 are formed, and the position of these openings is, as will be noted in Fig. II, such that communication is opened through them, between the air space beneath the moving grate-sections and the chamber within the castings. It

will further be remarked of "castings 7 that they cooperate with "angles 4 and 5. These latter constitute supportingledges for the moving grate-sections. The castings 7 con stitute on either side a guide for the gratesections when, supported upon angles 4 and 5, they advance in their normal and" intend ed manner. 7

The grate-bars 8 are particularly shown in Figs. VI and VII." They are formed asis usual with 'ertical grooves 13in their side] walls, to afford air passageways upward from beneath to the fuel supported above. They are arched as appears, and for pui poses already explained. 'They meet at their ends the edges of castings 7 in opposi. e faces which in the assembly arcinclined at a suflicient angle from the horizontal to afford rigidity. The gratebars are'further provided with downwardly extending perforated tangs or plates 14-, by which the as sembied'grate bars may be strung upon a' rod 15, or more accurately speaking a rod 15 may be thrust through the ahgnedperforations, and so the assembly be made more In Fig. T the position of the fuel within the furnace is diagrammatically indicated by the line a.

These characteristic features of my improved grate willbe perceived. First, the

support for the grate-sections, whiclritself necessarily becomes a grate element too, is

narrow Since the fuel is supplied by and initially upon the moving grate-sections 1 and 2, andspreads thence within the furnace over the stationary. grate element, the narrower the stationary element, the less the w is.)

spread, and. the more evenv the depth of-the ture the conditions of aerationthrough the stationary grate parts correspond to'tlie conditions through the adjacent movable parts. there is substantial uniformity in the rateof combustion on any transverse line, across the width of the furnace. tionary grate-bars being upwardly arched between the moving grate-bars, free them selves of ash accumulation. Fourth, this stationary grate-structure, serving also as a guide for the moving grate-parts, is itself composed of parts which are inexpensive to provide, simple in structure, simply assem bled, and are readily removable and replaceable. 7 Manifestly the grate-structure. in. a par- Third, the staticular furnace may consist of any number of movable grate sections and these will be supported at points remote from the side walls of the furnace by supports such as I have herein shown and described.

I claim as my invention:

1. In a furnace structure the combination with opposite furnace Walls and a grate structure extending horizontally from wall to wall and dividing the space between the walls into an ash pit beneath and a combustion chamber above, said grate structure being composed of a stationary grate-section and a plurality of movable grate sections, the stationary grate section aii'ording end support for said movable sections, the movable grate sections being pervious to streams of combustion-sustaining air from the ash pit beneath to the combustion chamber above, and said stationary grate section being hollow and ported to the ash pit beneath and to the combustion chamber above.

2. In a furnace structure the combination with opposite runways for the remote ends of two travelling grates arranged side by side of an intermediate support provided with runways for the adjacent ends of such grates, said intermediate support including a stationary foundation, a plurality of laterally ported channel members adapted to be removably mounted in alignment upon said stationary foundation, and a plurality of grate bars adapted to be removably mounted upon the duly mounted channel members.

In testimony whereof I have hereunto set my hand.

HARRIS l3. HOLT. Witness:

PERCY A. ENGLISH. 

